1. Field of the Invention
The present invention relates generally to liquid crystal technology and more specifically to a new material which does not scatter visible light to any appreciable degree. The novel composites of this invention appear clear and not cloudy to visible wavelenghts and function as a Kerr material. The novel material consists essentially of liquid crystals dispersed in a synthetic resin matrix wherein the droplet size of the liquid crystal is so small that it is substantially incapable of scattering visible light. Preferred are those materials wherein no more than about 15% of the droplets are greater than 0.1 micron in diameter. Particularly preferred are droplet sizes of 0.05.+-.0.02 microns.
2. Background Art
Synthetic resins containing liquid crystals are known in the art and have been the subject of various patents and publications. The most relevant prior art is World Patent No. 85/04262 of Doane et al, which was published on Sept. 25, 1985, the disclosure of which is incorporated by reference. Said published application discloses light modulating material comprising a liquid crystal dispersion in a synthetic resin matrix and the materials, resins and techniques utilized in said disclosure are equally applicable to the instant invention with one major and fundamental difference.
The entire purpose of the Doane et al disclosure is to produce materials which have the ability to scatter visible light, and their primary applications are envisioned as display materials. The instant invention is concerned with materials which do not scatter visible light. Thus, the material of the instant invention is diametrically opposed to the material of said published application. The major difference between the material of the instant invention and the material of the published application resides in the size of the microdroplets which are dispersed in the synthetic resin matrix. As has heretofore been stated, at least 85% of the droplets of the materials of the instant invention have a diameter no greater than 0.1 micron whereas the materials of the published application are stated to have droplet sizes greater than 0.2 micron.
Another pertinent publication is an article entitled "Field Controlled Light Scattering from Nematic Microdroplets" by Doane et al, published in Applied Physics Letters, Vol. 48, No. 4, Jan. 27, 1986, pp. 269-271. This publication is directed towards materials which scatter light and, at page 270, a graph appears which lists certain theoretical curves as to the droplet sizes of liquid crystals dispersed in a synthetic resin matrix. As can be seen, a theoretical droplet size as low as 0.150 micron is listed even though the experimental results show that it was not obtained.